Bug 509304

Summary:	SDDM fails to load after reboot when changing the wallpaper of SDDM, closing the settings window, and confirming choices in the popup window.
Product:	[Applications] systemsettings	Reporter:	2rakssoo
Component:	kcm_sddm	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED FIXED
Severity:	major	CC:	kde, kde, kdedev
Priority:	NOR
Version First Reported In:	6.4.4
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:	6.5.0
Sentry Crash Report:

Description 2rakssoo 2025-09-09 11:30:02 UTC

SUMMARY
SDDM fails to load after reboot when changing the wallpaper of SDDM, closing the settings window, and confirming choices in the popup window.

STEPS TO REPRODUCE
1. Go to Settings > Login Screen (SDDM).
2. Change wallpaper type and picture
3. Close the window without pressing apply.
4. Confirm the change by putting in the password.

OBSERVED RESULT
On reboot nothing loads (a blank screen).

- now when I change wallpaper it does the same thing - but haven't at first until i confirmed changes after closing settings window.

EXPECTED RESULT
Actualize wallpaper style and picture

SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 6.4.4
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.2
Kernel Version: 6.16.5-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i5-10300H CPU @ 2.50GHz
Memory: 16 GiB of RAM (15.5 GiB usable)
Graphics Processor 1: Mesa Intel® UHD Graphics
Graphics Processor 2: llvmpipe
Manufacturer: LENOVO
Product Name: 81Y4
System Version: IdeaPad Gaming 3 15IMH05

ADDITIONAL INFORMATION
I loaded back SDDM by:
rm -rf /usr/share/sddm/themes/*
pacman -S sddm --noconfirm
systemctl enable sddm --now
systemctl restart sddm
reboot

After that crash happened, I got those warnings on boot—they haven't disappeared after I brought the SDDM back:

platform regulatory.0: Direct firmare load for regulatory.db falled with error -2
spi-nor spi0.0: supply vcc not found, using dunny regulator
r8169 0000:0c:00.0: can't disable ASPM: OS doesn't have ASPM control
Bluetooth: hci0: HCI LE Coded PHY feature bit is set, but its usage is not supported.

nvidia: loading out-of-tree module taints kernel.
nvidia: module license 'NVIDIA' taints kernel.
Disabling lock debugging due to kernel taint
nvidia: module license taints kernel

NVRM: loading NVIDIA UNIX x86_64 kernel Module 580.82.07 Wed Aug 27 18:39:48 UTC 2025
nvidia_uvm: module uses symblos nvUvmInterfacDisavleAccessCntr from proprietora module nvidia, inheriting taint.

I previously received the same warnings after customizing the KDE shell, which also caused it to crash (KDE shell). I reported it using the automatic report option.

Comment 1 TraceyC 2025-10-09 22:22:13 UTC

I'm not able to reproduce the exact bug as described in git-master, but I see a different bug, which I'll file separately.

Following the steps to reproduce, the behavior has changed in a way that makes the bug, as reported, not happen

1. Go to Settings > Login Screen (SDDM).
2. Change wallpaper type and picture
3. Close the window without clicking apply.
4. A dialog appears "Apply Settings" asking me to apply or discard the changes. Click Apply. Enter password.
(If I click Discard I am not asked for my password and the window closes)
5. Reboot

Observed: The default image for the SDDM theme I switched to is used, I am able to log in
If I chose to discard the changes, the SDDM theme and picture that had been set are used, and I am able to log in.

I'll mark this as resolved for now. If you can reproduce this in 6.5.0 or later, feel free to reopen this report. Thanks!